I finally got inspiration for Pinkie's design! I was about to tear my hair out from thinking about it, I didn't know if it made her an earth pony, or a pegasus, or her mane with curls or totally straight hair, but I finally made up my mind! One day I post the list of characters that inspired each design.

Anyway, let's go to the mini description because I'm still writing the story of this AU:

Pinkie Pie does everything in the castle to help, from this visitor guide to being a jester, she is super cheerful but never ask about her past, she doesn't like to talk too much about it. Her hair is the way to know her feelings, when her mane is fully curled it means she is happy, if her mane is smooth it means she is sad. She knows absolutely everything about the castle, if you're in doubt about where something is, she's pretty sure she does.

Applejack is very serious, only speaks when necessary, few ponies have seen her smile, the birds tell that she is like that since the death of her parents when she was still a foal. She loves her family so much, she would do anything for them, especially for her little sister. She works as the head of the castle's cooks, her family has worked at the castle for generations, since the acre of apples was created. Applejack's design was totally inspired by the Applejack G1

Now a little dialogue because yes, there is no reason:

Pinkie Pie was walking around the garden, checking if everything was in place, after all it was the day of the Descendants to return from intensive study! In the distance she could see Applejack talking to a mare she didn't know, Applejack was even talking! That was something extremely unusual! Who was that pony that made Applejack open his mouth?

"APPLEJACK! APPLEJACK MY OLD FRIEND!" Pinkie yells at the top of her lungs as she trots quickly to Applejack. "Who would this pony be on your… side…"
Pinkie looks attentively at the mare, it was possible to see the horn from a distance but up close there was something different about her, she had wings…
SHE WAS A DESCENDANT?!
"IT CAN'T BE! You're one of the descendants, aren't you? I can't believe it, let me show you around the castle! Didn't you get tired of your journey? Don't your hooves hurt? Were the guards kind to you? Are you hungry? Where are you?" the other descendants? There were three, wasn't it?" Pinkie would keep talking, if not for Applejack's angry look, at the same moment she took a deep breath and looked at Starlight smiling. "Sorry for my manners, I was very happy when I saw that I was one of the descendants, forgive me your highness"
"No problem. I accept the tour of the castle, it's been years since I came here, I don't remember anything."
Applejack only saw the two mares walking away. It was time to go back to the kitchen.